// Copyright (C) Kumo inc. and its affiliates.
// Author: Jeff.li lijippy@163.com
// All rights reserved.
// This program is free software: you can redistribute it and/or modify
// it under the terms of the GNU Affero General Public License as published
// by the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// This program is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
// GNU Affero General Public License for more details.
//
// You should have received a copy of the GNU Affero General Public License
// along with this program.  If not, see <https://www.gnu.org/licenses/>.
//
#pragma once

#include <pollux/exec/vector_hasher.h>
#include <pollux/core/plan_node.h>

namespace kumo::pollux::exec {
    /// Assigns batches of rows to different partitions in a round-robin fashion.
    class RoundRobinPartitionFunction : public core::PartitionFunction {
    public:
        explicit RoundRobinPartitionFunction(int numPartitions)
            : numPartitions_{numPartitions} {
        }

        std::optional<uint32_t> partition(
            const RowVector & /*input*/,
            std::vector<uint32_t> & /*partitions*/) override {
            const auto partition = counter_ % numPartitions_;
            ++counter_;
            return partition;
        }

    private:
        const int numPartitions_;
        uint32_t counter_{0};
    };

    class RoundRobinPartitionFunctionSpec : public core::PartitionFunctionSpec {
    public:
        std::unique_ptr<core::PartitionFunction> create(
            int numPartitions,
            bool /*localExchange*/) const override {
            return std::make_unique<pollux::exec::RoundRobinPartitionFunction>(
                numPartitions);
        }

        std::string toString() const override {
            return "ROUND ROBIN";
        }

        melon::Dynamic serialize() const override {
            melon::Dynamic obj = melon::Dynamic::object;
            obj["name"] = fmt::format("RoundRobinPartitionFunctionSpec");
            return obj;
        }

        static core::PartitionFunctionSpecPtr deserialize(
            const melon::Dynamic &obj,
            void *context) {
            return std::make_shared<RoundRobinPartitionFunctionSpec>();
        }
    };
} // namespace kumo::pollux::exec
